SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a01bff18e50d574c9faed35d1aebfcd5e981eca1ac96608ec96def78293d07b' 
  AND token = 'rnuqfL45cSyCdSnXFsMNzmZo6VbfjxGmM2uReyaf8A8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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