SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'feab983fe89fbcda6ad98b6ab45ac3553520f6ad39aec12e581614a8a4381db3' 
  AND token = 'OuE/ov17wUMR5mFlipejm+BMPFvk2cL3k6mzImsJc5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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