SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3e4d66dbb9d604813408d002fe79ce7463ea11e30541ea550fda3609f830f13' 
  AND token = 'D4ot4+o89wBjmTUQp3nJiOMU4TyFiwRQhzdFgWpNvPA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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