SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75e50030482aa247c9f7f6c36c48d00c12d28c9916d413d6552eeb0cd84ac7c4' 
  AND token = 'AZsRFwfZSOTGQnUnjPTjiOuNdEWq/L5gW3yfDQHm0BI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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