SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55788e8265be6e2e86d3229046bc31666811f5f18b873713e31edd73e84b1bf6' 
  AND token = 'CwmPQAajlH0qGN2BHc9yFGngXmDo33YiySZ3gU6HEdo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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