SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '271742d524cdf8f5794aaab3d1c9e7afd4498e9676f59c9b6c2c9f578b4639b8' 
  AND token = 'LKQtxneN0xEuhwYXkABe/SrN9J1GNV9LDsJjJyvsagI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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