SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3b2daea7e97be288420486e55da2299501b8f9146d6df1609b5aebf919543f5' 
  AND token = '7UGlqNOeND7djJxG8Ey5/Hj+icaE9N3rkZ0q9xukIJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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