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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b4bdf439b56d3f20d28dca950b5b1959dc56f96e8d9cad02db98c3526ebb136' 
  AND token = 'y1rnVfG+cmQYImFSHA/Wc3D/ty5gO7NNRN6urYvzQkg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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