SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5e6e7891804da2524b518b31ccdbd5e466a09c498d39cf64670d49649234976' 
  AND token = 'Nw98jwLFBPAUUdCz+xlFh2r1cFUV2QqqmTP0Fhsfng4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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