SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88ffb80767dcdcf509f97f75469f9296fbad781ec490e2d52eb53a517bd95e3b' 
  AND token = 'CeCfJ1s7jozvQPk0ZgfxYVCTrzzKQjWYPxiVrWd+tUs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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