SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6274fa875a2c82c16654d6cd10387d10ec602263b55aaf0c47a1ee546e4e3fa2' 
  AND token = 'NrFdlsUWOrMILfIe3OnyEo1wIw/LSWYeE1dUTbD9Sr4=' 
  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"
    }
  }
}