SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2f9b752ca5fa33d00544dd639bf439f81baa5436ddf4ff076768df894096b9f' 
  AND token = 'hTLeX/y3Z9FhoPS7DBs01tVulPdLKVIcgQwnQyn/gFk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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