SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1d78cf64f7fef9c0617776bb0ea746767008947beb048649e485524f76a6b51' 
  AND token = 'xekSR+fn6MtkGyP54oeL9FK/JnYH/naTYCqFmKLxiO0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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