SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5518d56e66cc7743cd1a8abdaf19701ce526e31e0320259633cde76f56c612fd' 
  AND token = 'AiEHw85ij0V6C85bcykr4G+TMIc79xyi6HCWCZjaecw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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