SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b64498c2d8923164e1f2cb7a82d813296e71cf29bafa1547577030d90591095' 
  AND token = 'Kziu5pr+VdJeK/KyLF3irmOIbQGftkLhlFI6wADzlfs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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