SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f61dc701a0e11730c1586168ff3feba266166b5e568126e783affb0404845aa8' 
  AND token = 'imxajCzqavt62hR2ZBSBeCgzgQQtEhUYJ4m1dXRAHCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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