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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '8b9a1134bf2ce9e5e489458025bdecb50e3383a19b1d1ccbd9d2b4a1a8984dcf' 
  AND token = 'a4zUiQtXiosghWgAPQ4EfjzYg3IDH3EdXiSusdEUHiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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