SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e256afe6594f4ed6e8086ae33659bc23981a6b4fc18ee7ebeb52297a7cfbb5e' 
  AND token = 'j4NPYqstfKhNX32CAlcGiG84zu/Y1JBk3Qtm8xEmAxc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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