SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bef45c3d02c2fb4bce914695c8329e1da01cdf645673b4f450f37e0c603cea89' 
  AND token = 'mG9JzQIWmsvDeERxL22N7ka7bW3DeuKiHoVKUKo/gyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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