SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a8c999fec6d729f77885d684136986b059cadab3cf78336b536fa18963696f4' 
  AND token = '88WHfC4tFAWnDceIRmai7AcNNdEEpTSM+TmPb2r1SAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}