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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '878818972d3255d2db1acc5a8a48a040d7b9ea776d28fbdfe6f2c2fa146ad608' 
  AND token = 'rTGERBVyqnNprmsz/W1LairIRlDKuIaA+1E+espTIsg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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