SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '860e34a7710838b481c0755a7b82febf93e85afe14148ccac74cb6b0be926937' 
  AND token = 'MzbMjyGGEvLFPys3GFl8nexW/ElzIEVPaUemh7C35qc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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