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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d77cb6a0540664366d741244b39ee0cf5033005fb6f27c58c2efb9ca477083f' 
  AND token = 'PpiQo0RBHCprbR7CXdEqt8F1/wfN58xdjH8VUU2aEcg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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