SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ebc8bc2f609711f50609f83671ebf84a0efd0a936bcf73ad24152f1e4fe6a623' 
  AND token = 'n/TGtWQwqZYsK4oZwfhcTc2pVBl44S0danoOoMRdz5I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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