SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a37edf096ca19cb937cadffa22fbf68cfb1d6237621df09d844add98b4193e17' 
  AND token = '6MakAQAniwPoIW3Em+WMma+xdtL3Q17rWN46ryqVeAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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