SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7725d7d6bc41deb29c71852d845d93fe4f67ecb581adf83bee5edbb98732a33a' 
  AND token = 'N71+HmyMcHNtTlz9wKXsZSU6DhjYzUyd/zjTefe1sow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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