SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6eaad1c02a9870d33263a4fec4dddfda71bfad8571738da178d0ee4f54d3a3b8' 
  AND token = 'SZ3p8DfAerS2JjDjeYUbbpuntAXZODjn2i2xKPI31us=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}