SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8611d29aa43e55fa8a4a77fba10345a07d2ee2da14f108c2b283cf23df413127' 
  AND token = 'EnlAxqkgwQ+dgr2YeEaUNokHNkR2S+VRYUpCsNoexeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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