SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb8167e0f1867b97260ee3c0860d4752b37d3d5d28a812945c8becacdd263a49' 
  AND token = 'TNVigy1DkALenZbtjuw4tHoRTEj5i/AnVCwN5jlKfS8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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