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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4a258428c64fbf5eab04ffdda4f6600a7d3e3fdee2a727bcde9d9f7da4885bf' 
  AND token = 'gx97aQxCHAVMPhNBIKReSzY38Ced+6c5S0GvnpAg1Qk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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