SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ee36410794df8a93bb2ff25519c6c914be8cc7a9d9718f141c5a340e7d18eb6' 
  AND token = '7ey41IG8AbblwWbF2IuiG1uQ9U1oF5MYpuetMpskGG8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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