SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b48f15c8e2abb9d2cf05908a1b71fe2783e03a2af1119a43d01559252828241' 
  AND token = 'iimG1YviOqTsArtp1SG4ASvXS7UK02Wzb8bbLBUOE0g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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