SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4bfde6c967ceef2e9ca087fe874153a4d60928ead52d611f9cb2c7b0bf5915b' 
  AND token = '3cAjQt0a3hh2uZXlWSOwCoGhrvyzz9ANcJYYSSGIVbY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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