SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52ac98eafa2dd2407560b02be348de7b5be80aaf7a2b951113334da3ea82a1bf' 
  AND token = 'DzCeJPeMzAzig+FGwC6F17G4VIxHnp9s3Qn/kOsEtNE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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