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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '958c18d3c3662105e6d3a30d6cd5a14112712c0769f7cdf796e0fbfd2f5db356' 
  AND token = 'zR36gLzNh/mIxAXkddvj3qPDoXgx1kvt3jkctJTeiAA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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