SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a68a6dd87c0b3eee0724c55e5ad73e157863eb8a080293b8c1da49f81437b5b' 
  AND token = 'azgg55FvhuVtBfhZvkJnidCRKGr+lynWB65zGnfZ0QE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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