SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '950413524c0e389b90015cedee6a9d68bc4f2cb0a1011ee0b254bdad012ecb33' 
  AND token = 'ugsvvgJWkAG5VrzCnidyEdmBg8K7vo6yWLZfOCXPsdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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