SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec8ee583216f25156db35c5a438e422bdfc1186aaa83b75997ac8b188efe9c1e' 
  AND token = '1IfBveTCbJmt0SD7bto6kUJxMVDbAfeihXADh7xJLx8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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