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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6d8d7b5bdf00937dd14f2a88286352c5ad1ac1c1d5b12a56e2fc73e34c4fe3f' 
  AND token = 'pELtAWqaOKBqeJvuH4UuYCWiwlXakeO85lia67Aa0dU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}