SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f763526264ded8b3c200fab65b39fb092946803dbab291bc2f8532b3fa1c00f7' 
  AND token = 'f5b4LMtBKCRANwHHpBqATJ3nzuNiy5GcQbu9wlCIkZc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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