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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03522a3ea5acd93ff907f1dd50cf10267e32e0c73c10a6870081389aa1ac1aca' 
  AND token = 'XQ0BhUTjY3zI+CLYQeXTOVwtYeOT+aIk0c5SO+EoqQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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