SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18454978e54a9793f2503336847c933f403e18c85717b3e30b451315d472b06f' 
  AND token = 'mu5IK5eajSh7+3z2YTtoJCxdHvqQOWJAdaY+nQwDeGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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