SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd537c460cffd15147276bab2ad341f2c6ba0340ab98283b9e2a0b793489869da' 
  AND token = 'AGjOyjNeaijjjZFkz9CBNObosAmMKbCrR/OlYQ9m/Xg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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