SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '387a26500fb9efbcdae111b25ed4c58d80b3c9ad4ef06040c324d85ea3a0cfc7' 
  AND token = 'rqHc7sy/wbfqR/s1UZ9rbARCVCQ9FoHNj+EHnPZCIso=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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