SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fb5cfc8707730c963b2247df729cf413a1a3284bdf786535a6f28b41d3eba10' 
  AND token = 'gckwo/RwOG1/Yc/ispX7mkHZIDMsSzIJBkmIm58sjKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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