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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bd695cbbf40f18c8b0c2a52e66cd537bf3d211ab8cdf2021187c8814d6ca7f04' 
  AND token = 'DNGiOzmzudcvpgKvQCHtNS9CP8pij1QpgYEBvnKDTcU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}