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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81ceab7533f8feb6cb098906ab907b89a2a688cff90b42ac1491ffaf23e2ca9f' 
  AND token = 'UDjxpnLD5V7hpqMPp5Qf8fYGeL1d/Lu8NzqDDVYgs34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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