SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '988d44665d2194ba27b5ed8d64c8c9ab8a2109be01aadfd242925bc14435f650' 
  AND token = 'l4mtLO7ec+BWUgxcY17gkjXvi7W2AhzfMnV16WU0chk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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