SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8dd0833e4e2c8d03d58390e3870fcfca1640e0f4e1662a12ef1f6cb805e998c' 
  AND token = '85wlVuCQt6idIamTTbFpw1eTOx78pObMULy7z0+RCwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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