SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d74850ee0116173fc648f69c6baa1cade8fdf0272f5290e0ecbbdbd5d7b4f6b' 
  AND token = 'BU8k/9EdzchqZJyriAQaTQYiLw+Y3rE8zgS9Aa7pdWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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