SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bd94dc75e5d1bddb159f161317418b3795fb383df89bbd5b098de03b43c653f7' 
  AND token = 's/WaquSPKyH7Kt76WD2WFyCFYFGWq7/qtLNuVVNMahE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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