SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e45cdc3b87bfd8a570418645b0defb38a59fc119a0d97916e554235685341a4f' 
  AND token = 'K29eBBMZCaDTxGuejpGfceCiiDhZJst30NpGDvraMQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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