SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f250479e31e918e9d6bb9190aa53685ea4397ff526f315d1380ea0e5ff96af49' 
  AND token = '4jXNLat3BrlyYcCqq2EAxqbMaTJwPQCNK7JoVI3MGVM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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