SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f73752e187110811fd59bf5930aac6f4fd77889e61e0e101cf8fbdd306842f5d' 
  AND token = 'gjRdLguUYBwUJMjCSTFjbnfAm7MpSPe5hvvudoV/t3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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