SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12dacd017a5d307e8d5f58120584109714a8f65a6240db7eff977f9cad0b311b' 
  AND token = '+Z1DnPvmClj58Y8g1QM6CUAa3mzQ8om9Er2/Y2XF97Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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