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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad759e84bccff009a0aee148d7c154dd3752b4b262ba2a56098ab1d3bc530c2f' 
  AND token = 'fMLQ0ZeyNUeKuE2XZ0IQvSJClmGDI4c6Ayt9Ny2Gm00=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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