SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdd8fd88d8f7bae05e40a46949f32dbedfc26a6abea81f5800b3bdc677835997' 
  AND token = '+39t8ywPh+FqhU8j8x8GjaseJvWzLKyEQ3RFe1gBj+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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