SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ef6871741f59168e2d57989369ab9b43750a12fdd1b1d744c711a69e4eb4724' 
  AND token = 'fu6GFSL0x//SOqSING8hK78A/bsYSuU4/BG/F5V0Rzw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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