SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '856288230d43213151042866d75d7c60a68dafef3c9513ebfe89a33b920c3252' 
  AND token = 'Vn5Jg3IK/OyBsx0LylKhrv7dsVIUpLuMOHncWE9x09c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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