SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90874f0b0f842fe3d0ce6639171841c65f067a6e69e532ffa0efc3b748aeb0a8' 
  AND token = 'F0Xavl33KRP6LBLQEQrRyJvZiWBXMliCZVgN3wVZ5Ug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}