SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9750599cb1eda5f4a27cc733bbccd5fefa872c9b52cc8aae5530118f936f0a8' 
  AND token = '4+VJO6YvrK4xz68oJvKDHOCCvyos5+DfgGDfI1d3oto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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