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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f437d4a7a560dc7c9d695789e415090d45da6bda3e3edd12cbb9e8a996cbc7f' 
  AND token = 'DH2/Bbf8XMjsH7fABc1nIa6fmyThQv1bO2en2JhJltk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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