SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b688a748ca9ee0945631b1027b80bfd12f00d6f02c0e07004e43c33d8a6a8cfd' 
  AND token = '+b/KiYVwNkzX7eBlGle+Z2H94oIO2WF0Nnhz7/q6X6g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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