SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71e30b6d4bbce868420e9af94a63fbd30e3a44501be5f204386f35eefbfb075e' 
  AND token = 'arSE0xYJLP9e4eikZbglVeF+dv+pStz3ojjChXr/jeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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