SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2374fa0afa2ea46c8fa0ebcd6131de5c05803ccafcda9076d94b1c80827a14f5' 
  AND token = '3NiaJffxAGTaQxDbMVQPZSOSFwmhr8qyQqDDSBPDY+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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