SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55bc089cf50e3ea8f48e592bddbc5bf2b15fd9cae040507a6e3da65c273e0aed' 
  AND token = '6GsD2pwG6qFHvjAZYKkI4y+6/8zX1pgqgcYvAkaN3zQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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