SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79137fe256299424b278bf6fc0d1ae0270593e51050cb8dc12d849c137b54a68' 
  AND token = '+n05bEnTbqBrBOAVEDroegNs/SP9ItsymLLSA0hghH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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