SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2942ef336888d9f2eb02faf5f699c3b1292de7a6485a71b5e257fe0d9dcbb1e9' 
  AND token = 'OTpKTQwqRl9b7sKWoKW9ARxdLp8Z0rnkiSHtPIBdrNs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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