SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7fa8243578119b180ef4e30592aced94223b16563fcc8153ff3dbb9c0243265' 
  AND token = '1FlIcsXLQ+QI41+yvWJGBsp7hxfps3+ehd4x+CYVCzc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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