SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c64ddc350061cb298ba9bd96dfd856d8c001cff691610f4114c785d04c387941' 
  AND token = 'GZnGuD1TdwKxgJg52rXhvnEJ0HcXfgBhWlhY2Z28iQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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