SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29bc6509483d3e27225ae203cdd509e28b2565f257b0acb40d708125abfead01' 
  AND token = '59A4dNKAvYdWt3WnazlKs8LYC0xfX84/owKC1XSNx+o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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