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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c8aa708dd5585413e9340932646eccf83499fefdf9d44689ec17584d3df8a91' 
  AND token = 'f3vYax33namZjb5/vbMXnd9rl9BEirb5FuwyrehC4dw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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