SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f278b15f143cc2818ccefb1429c29f906206bf1cb3e55f5ef5b23b8d97d086a' 
  AND token = 'lAy6jcLU00mCv1nK/svMIPo65tUmh9W6i3a0A+A/fco=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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