SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21097d881316f934c23fa723677ccd09146cbbe992a00f1f0797eaedfa22fd08' 
  AND token = 'MS42/ldhodFNlSGjUePCxEoGncPHXoErM4KFTz8dlG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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