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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4feb5d1133ec81d9273673790e2ee162cec5075e109ec7c8695573c06ed1c721' 
  AND token = '76G9xVR4PYOxoljto+VcePCZYdKUHjeNvjtEM3aPdwk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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