SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f5381de5c97a7a360e0286daa4e3074df0673520eb2c192faf7f9b2f60a7a98' 
  AND token = 'RefLSn5L/lwYmBjDwpDISlzjAOM/WcCnqFshQvPOSKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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