SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '858da37ec13aa45dadb41211c8808e44e45be53c70a8ab3b32e4e2d36a11e928' 
  AND token = 'aaEl/1xLfE2l8NZWEoFPnrogEiCSEx1heK+KyB24kVY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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