SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cb575687f4cfc4c1ac38cc09ac43f2f315959ca1724001637445d0eade8faee' 
  AND token = '+eDu+8qmd5D1vx+wSPUqBeP7Dq2FuRZgdzfqoR4iWRo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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