SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '712d5a23413a0341149b453b25326ca2d7ff313a09cc32eefb111ff8e50394c2' 
  AND token = 'SBeada+aYF/FfJZra4Ixh6dzwircetYfajvwox6DF18=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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